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論文

Search for $$X(3872)$$ and $$X(3915)$$ decay into $$chi_{c1} pi^0$$ in $$B$$ decays at Belle

Bhardwaj, V.*; 谷田 聖; Belle Collaboration*; 他191名*

Physical Review D, 99(11), p.111101_1 - 111101_8, 2019/06

 被引用回数:6 パーセンタイル:41.49(Astronomy & Astrophysics)

We report a search for $$X(3872)$$ and $$X(3915)$$ in $$B^+ to chi_{c1} pi^0 K^+$$ decays. We set an upper limit of $$mathcal{B}(B^+ to X(3872) K^+) times mathcal{B}(X(3872) to chi_{c1} pi^0)$$ $$ < 8.1 times 10^{-6}$$ and $$mathcal{B}(B^+ to X(3915) K^+) times mathcal{B}(X(3915) to chi_{c1} pi^0)$$ $$ < 3.8 times 10^{-5}$$ at 90% confidence level. We also measure $$mathcal{B}(X(3872) to chi_{c1} pi^0)/mathcal{B}(X(3872) to J/psi pi^+ pi^-) < 0.97$$ at 90% confidence level. The results reported here are obtained from $$772 times 10^{6}$$ $$Boverline{B}$$ events collected at the $$Upsilon(4S)$$ resonance with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider.

論文

Search for a light $$CP$$-odd Higgs boson and low-mass dark matter at the Belle experiment

Seong, I. S.*; 谷田 聖; Belle Collaboration*; 他191名*

Physical Review Letters, 122(1), p.011801_1 - 011801_8, 2019/01

AA2019-0529.pdf:0.35MB

 被引用回数:16 パーセンタイル:75(Physics, Multidisciplinary)

We report on the first Belle search for a light $$CP$$-odd Higgs boson, $$A^{0}$$, that decays into low mass dark matter, $$chi$$, in final states with a single photon and missing energy. We search for events produced via the dipion transition $$Upsilon(textrm{2S})rightarrowUpsilon(textrm{1S})pi^{+}pi^{-}$$, followed by the on-shell process $$Upsilon(textrm{1S})rightarrowgamma A^{0}$$ with $$A^{0} rightarrowchichi$$, or by the off-shell process $$Upsilon(textrm{1S})rightarrowgammachichi$$. Utilizing a data sample of 157.3 $$times$$ 10$$^{6}$$ $$Upsilon(textrm{2S})$$ decays, we find no evidence for a signal. We set limits on the branching fractions of such processes in the mass ranges $$M_{A^{0}} < 8.97$$ GeV/$$c^2$$ and $$M_{chi} < 4.44$$ GeV/$$c^2$$. We then use the limits on the off-shell process to set competitive limits on WIMP-nucleon scattering in the WIMP mass range below 5 GeV/$$c^2$$.

論文

Observation of $$e^+e^- to gamma chi_{c1}$$ and search for $$e^+e^- to gamma chi_{c0}, gamma chi_{c2}$$, and $$gammaeta_c$$ at $$sqrt{s}$$ near 10.6 GeV at Belle

Jia, S.*; 谷田 聖; Belle Collaboration*; 他191名*

Physical Review D, 98(9), p.092015_1 - 092015_8, 2018/11

AA2018-0763.pdf:0.43MB

 被引用回数:7 パーセンタイル:41.87(Astronomy & Astrophysics)

Using data samples of 89.5~fb$$^{-1}$$, 711.0~fb$$^{-1}$$, and 121.4~fb$$^{-1}$$ collected with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider at center-of-mass energies 10.52 GeV, 10.58 GeV, and 10.867 GeV, respectively, we study the exclusive reactions $$e^+e^-togammachi_{cJ}$$ ($$J = 0,~1,~2$$) and $$e^+e^-togammaeta_c$$. A significant $$gamma chi_{c1}$$ signal is observed for the first time at $$sqrt{s}=10.58$$ GeV with a significance of $$5.1sigma$$ including systematic uncertainties. No significant excesses for $$gamma chi_{c0}$$, $$gamma chi_{c2}$$, and $$gamma eta_c$$ final states are found, and we set 90% credibility level upper limits on the Born cross sections ($$sigma_{rm B}$$) at 10.52 GeV, 10.58 GeV, and 10.867~GeV. Together with cross sections measured by BESIII at lower center-of-mass energies, the energy dependency of $$sigma_{rm B}(e^+e^-togammachi_{c1})$$ is obtained.

論文

Evidence for isospin violation and measurement of $$CP$$ asymmetries in $$B to K^{ast}(892)gamma$$

堀口 朋裕*; 谷田 聖; Belle Collaboration*; 他191名*

Physical Review Letters, 119(19), p.191802_1 - 191802_8, 2017/11

AA2017-0510.pdf:0.3MB

 被引用回数:17 パーセンタイル:74.18(Physics, Multidisciplinary)

We report the first evidence for isospin violation in $$B to K^{ast}(892) gamma$$ and the first measurement of the difference of $$CP$$ asymmetries between $$B^+ to K^{ast+} gamma$$ and $$B^0 to K^{ast0} gamma$$. This analysis is based on the data sample containing $$772times10^6$$ $$Bbar{B}$$ pairs that was collected with the Belle detector at the KEKB energy-asymmetric $$e^+e^-$$ collider. We find evidence for the isospin violation with a significance of $$3.1sigma$$, $$Delta_{0+}=[+6.2 pm 1.5 ({rm stat}) pm 0.6 ({rm syst}) pm 1.2(f_{+-}/f_{00})]%$$, where the third uncertainty is due to the uncertainty on the fraction of $$B^+B^-$$ to $$B^0bar{B}^0$$ production in $$Upsilon(4S)$$ decays. The measured value is consistent with predictions of the standard model. The result for the difference of $$CP$$ asymmetries is $$Delta A_{CP}=[+2.4 pm 2.8 ({rm stat}) pm 0.5 ({rm syst})]%$$, consistent with zero. The measured branching fractions and $$CP$$ asymmetries for charged and neutral $$B$$ meson decays are the most precise to date. We also calculate the ratio of branching fractions of $$B^0 to K^{ast0} gamma$$ to $$B_s^0 to phi gamma$$.

論文

First observation of doubly Cabibbo-suppressed decay of a charmed baryon; $$Lambda_c^{+} rightarrow pK^+pi^-$$

Yang, S. B.*; 谷田 聖; Belle Collaboration*; 他191名*

Physical Review Letters, 117(1), p.011801_1 - 011801_6, 2016/07

AA2016-0388.pdf:0.49MB

 被引用回数:32 パーセンタイル:85.28(Physics, Multidisciplinary)

We report the first observation of the decay $$Lambda_c^{+} rightarrow pK^+pi^-$$ using a 980 fb$$^{-1}$$ data sample collected by the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider. This is the first observation of a doubly Cabibbo-suppressed decay of a charmed baryon. We measure the branching ratio of this decay with respect to its Cabibbo-favored counterpart to be $${cal B}(Lambda_c^{+} rightarrow pK^+pi^-)/{cal B}(Lambda_c^{+} rightarrow pK^+pi^+)=(2.35 pm 0.27 pm 0.21)times 10^{-3}$$, where the uncertainties are statistical and systematic, respectively.

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